The isothermal and cyclic oxidation behaviour of Ti-48Al-2Mn-2Nb (at.%) were studied at high temperatures in air in comparison with the intermetallic alloys Ti-48Al-2Cr-2Nb and Ti-48Al-2Cr. Tests were performed in air between 800 and 900C. Two-stage oxidation experiments with isotope tracers were performed to study the oxidation mechanism in more detail.